Host—parasite relationships ofBlastocrithidia familiarisinLygaeus pandurusScop. (Hemiptera: Lygaeidae)

Abstract

SUMMARYBlastocrithidia familiaris were found to be parasitic in the midgut, ileum and rectum of Lygaeus pandurus. The host—parasite relationship is described. Attachment of parasites in the midgut and ileum occurs by interdigitation of expanded flagella over and between the microvilli. No attachment to microvilli was observed where extracellular membranes form well-organized layers which lie parallel to the gut wall and completely separate the microvilli border from the lumen. The extracellular membranes originate from delamination of the outer unit membrane of microvilli which consists of a double plasma membrane. The function of the extracellular membrane layers and their possible role as a peritrophic membrane in preventing parasite attachment is discussed in relation to previous studies on midgut cells in Hemiptera with a similar apical coat on midgut microvilli. In the rectum, parasites attach to the cuticle of the gland cells and not to the rest of the rectal wall. Attachment to the cuticle occurs by the formation of hemidesmosomes. A comparison of the relationship of B. familiaris and its host to previous ultrastructural studies of associations between kinetoplastid flagellates and their respective hosts is discussed.

Penetration of the salivary glands of Rhodnius domesticus Neiva & Pinto, 1923 (Hemiptera: Reduviidae) by Trypanosoma rangeli Tejera, 1920 (Protozoa: Kinetoplastida)

“…In most trypanosomatids, the parasites adhere to the digestive tract of their respective insect hosts and form a homogeneous cellular layer as a critical step in their life cycle (Tieszen et al 1986(Tieszen et al , 1989Molyneux et al 1987). In vitro studies on the interaction of T. rangeli with dissected fragments of the posterior midgut of R. prolixus showed few parasites attached to sparse epithelial cells, suggesting that a recognition step is necessary for posterior invasion (Oliveira and De Souza 2001).…”

Two New Species of Trypanosomatid Parasites Isolated from Heteroptera in Costa Rica

“…Second, the flagellar cyst-like cells (straphangers) and free cysts are observed in this species, as they are in B. triatomae, B. leptocoridis, and several other species of Blastocrithidia (Cerisola et al 1971;Schaub et al 1990;Wallace 1966). These cysts represent the products of unequal cell division characterized by condensed cell content, the lack of a flagellum, and formation of a dense cortical complex under the cell membrane (Peng and Wallace 1982;Reduth and Schaub 1988;Tieszen, Molyneux, and Abdel-Hafez 1985). In B. triatomae, such cysts were reported to be resistant to adverse environmental conditions (Schaub et al 1990) and serve for more efficient dissemination of the parasite.…”

If host is refractory, insistent parasite goes berserk: Trypanosomatid Blastocrithidia raabei in the dock bug Coreus marginatus

“…In the anterior segments of the midgut (M1 -M3), the interaction of B. raabei epimastigotes with the host (attachment with the dilated flagellar tip in the zone of microvilli causing their degradation) is similar to that in other species of the genus [33,[63][64][65]. However, due to the peculiarity of the host midgut morphology and physiology, starting from the posterior funnelshaped portion of the M3 segment, the behavior of B. raabei becomes strikingly different from what has been described in other species.…”

“…The morphology of CLAs and the process of their formation also do not differ from those in other species of the genus [60,[77][78][79][80]. Peculiarly, for the attachment in the rectum, B. raabei uses the extended lateral flagellar surface, rather than a dilated tip or a flattened attachment pad, which are inherent to other trypanosomatids inhabiting this intestinal region [63,65,[81][82][83][84][85][86]. However, this mechanism has been previously documented in epimastigotes of African trypanosomes developing in salivary glands or in vitro [87][88][89].…”